


Forbidden For The Holidays

by Dark_Crystal_Demon



Series: Forbidden [1]
Category: Undertale (Video Game)
Genre: Because it's the holidays and we should end with, Bisexual Female Character, Chapter 3 Warning, Chapter 4 Brings Back The, Cheating, Consensual Kink, Consensual Sex, Daddy Kink, Dom W. D. Gaster, Ecto-Penis (Undertale), Ecto-Tentacles (Undertale), Ecto-Tongue (Undertale), Happy Smutty Holidays, Master/Pet, Multi, Non-Consensual Bondage, Open Relationships, Pet Play, Possessive Behavior, Sub Sans, Tentacle Sex, Threesome - F/M/M, Undertail, and, with a little
Language: English
Status: Completed
Published: 2016-12-20
Updated: 2016-12-31
Packaged: 2018-09-10 14:13:14
Rating: Explicit
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 5
Words: 11,866
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/8920258
Author URL: https://archiveofourown.org/users/Dark_Crystal_Demon/pseuds/Dark_Crystal_Demon
Summary: You're in an open relationship, but your girlfriend has two rules: no marks and no kissing. They seemed like easy rules to follow, and you thought you had it under control until you realize that some skeletons don't like to follow rules... and your own attraction to possessive personalities is only going to get you in trouble this holiday season.





	1. Before the Party...

**Author's Note:**

  * For [RavenZaphara](https://archiveofourown.org/users/RavenZaphara/gifts).



> This is definitely NSFW for language, sex, and more sex. Please don't read if you are under the age of 18.

Your office holiday party is tonight. Your hand shakes as you put on the finishing touches to your makeup. You keep tugging at the little red dress Sans had bought for you. It was very short, very tight, and very... unprofessional. Could you really go to the party like this? 

"Where did you get this dress?" your lover nuzzles your neck behind you. Smelling your hair, she wraps her arms around your waist and hugs your curves.

"I bought it yesterday on my way back from the lab," you lie. You had been doing that a lot, but your lover is too distracted by the silky texture of the dress and the way it glides over your body. You purr as her hands begin to pull the fabric up until your dress is above your hips.

She slips one hand under your panties. "You're fucking irresistible in this dress."

You gasp as two fingers surround your clit and dip in slow circular motions. She nibbles playfully on your ear lobe, "I may have to cancel my date and go to this party with you, after all."

"I... told you... you can come." It's hard to concentrate as she pulls one of your breasts out of your dress and squeezes it roughly. Her nails digging into your skin, she presses her body tightly against your back. She's so... soft. So different from...

"And ruin your date with that skeleton? I'd rather not come between you and your boss. But I will remind him who you belong to," she dips her head down to your neck as her hand circles faster between your legs. She squeezes your breast again, bites into your neck, and starts to suck, _hard_.

"No...Ah!" You try to pull away from her mouth, but your knees go weak as the pain pushes you closer to the edge. You had a weakness for aggression and you'd be lying if you said you didn't enjoy her possessiveness. One of the best parts of this open relationship idea was that it had brought this side out of her more.

She enjoyed marking you.

She enjoyed the idea of others having you and not being able to do the same.

And you...

You enjoyed the tease.

She looks up at you in the mirror and enjoys her handiwork. You arch your back as the muscles in your stomach tighten. Her fingers increase their speed with an expert squeeze that has you cumming against her hand. 

"Ahhhh!" You grip the counter to keep your balance and she kisses your shoulder blade as you shake in pleasure. Hugging you against her, she says, "You're so beautiful when you lose control."

You look up at the mirror and examine the crescent marks along your breast. Thankfully, she didn't break the skin; however, the new red hickey on your neck was not going to be as easy to hide.

"Your mine." 

She turns you around and pushes you up on the counter. You wrap your shaking legs around her hips as she cups your face in her hands. "I love you." You're still panting a little as she takes your lips with hers. You breathe into each other's mouths, and she dips her tongue between your lips, claiming her territory. 

You slide your hands under her shirt and drag your nails across her soft skin. She purrs and nibbles on your lower lip. "You have the most perfect lips, love. And their mine. Don't let bone boy forget it. Kisses are for lovers."

"I know. You trust me right?" you kiss her back and hate yourself as she nods. She shouldn't trust you. Because the truth is, you have been losing control of the situation since the moment you met Sans...

At first it had just been a casual fling of curiosity.

The first day you met, you shook his hand as he welcomed you to his team. You'd gasped at the electricity that raced up your arm from his touch. Everyone around you thought Sans had just played a joke - the old buzzer in the hand trick - but there had been no buzzer. You shook the feeling off with a small laugh, "Must be static electricity..."

He agreed with a "Sure, kid," but his eyes followed you the rest of the day. He caught you examining your hand that kept tingling even hours after he'd touched you. It was your first real exposure to magic.

You went home that day and studied all your old notes on monster physiology. It had been a required course in college since monsters had come back to the surface. You were in your junior year of your Physics degree when they emerged, and you had thought the class was a ridiculous requirement back then. As you flipped through the pages of your notes that night, you ate your words and silently apologized to your professors who had prepared your ungrateful younger self for your first job with a skeleton boss.

You learned that skeletons were some of the purest vessels for magical activity. It's how their bones stayed together (among other things). But there's was nothing in your notes about shocks. You started to examine you colleagues interactions with Sans, but they didn't exhibit your sensitivity. 

You weren't the only one who noticed. The first few days you had to work closely with Sans to learn the routine. The hair on your skin raised at his proximity. When he was teaching you the computer system, you nearly jumped when his finger bones grazed yours on the keyboard. You apologized, but he barely acknowledged it as he stared at the goosebumps along you arm. You noticed his bones bumped into you a lot that day and you got the feeling he was running his own personal experiment.

Not wanting to be known only for your static jumps, you took matters into your own hands so that you could be taken seriously. It was summer back then, but you started wearing long sleeves and gloves to work. With practice, you successfully avoided touching him directly. You became excellent at dodging even the simplest of movements.

It became a game. You watched him watch you. You made him acknowledge your work by always volunteering to share the latest reports without your gloves on. His hand would touch yours as you passed him the folder, and you would shiver, biting your lip. You could see by the tension in his shoulders and the way he rubbed the folder in his hand that you were teasing him...

...and that had always been your favorite game.  

After a few exchanges, curiosity got the better of him, and he got bolder. His hand lingered; his thumb rubbing small circles along your the back of your hand. You tried to pull your hand away, but his grip... was a lot stronger than you expected. "Describe it."

"I..." you didn't know where to start. 

"Close your eyes, kid." 

You bristled at the nickname but obeyed. You relaxed your hand in his.

"What do you feel?" His voice was so gentle, it threw you off. He was serious in his desire to know. This was becoming less of a game... Your boss's hand covering your own...

You took a deep breath. That was the first time you noticed the way he smelled like those ketchup packets he snacked on and... smoke? You'd never seen him go on a cigarette break. Did cigarettes even effect a monster without lungs?

Stop rambling to yourself. Feelings. He was waiting for your...

"Your magic pulses," you start. "I'm... sensitive to its wavelength, I guess? Sometimes you shock me but I don't know - Ah! you just did it!" you exclaim as you open your eyes and read your answer in the desire within the lights of his eye sockets. "Oh..."

Primal. That was the only way to describe that moment. His magic rippling through the nerves in your hand and traveling up to the beat of your heart. His eyes held a question you had seen so many times in your life, but never from a monster. All he needed was your consent...

But then a knock came at his door and you both jumped. He released your hand. And awkward moment lingered as you both remembered where you were... and who you were.

He's my boss.

Still, if you got your lover's permission...

"Perhaps," you licked your lips that had gone dry under his gaze. "Perhaps, we could continue these observations later this evening?"

Sans nodded, not trusting himself to talk. You stood up and opened the door to let the next person in. "I'll have the rest of the reports on your desk at the end of the day, boss."

And that's exactly where he found you later that night, on his desk, waiting for him. You laid out the rules of your lover, "No kissing and no visible marks." Sans found no problem with either. It was the perfect arrangement for a casual fling. At least, it would have been...

That night, he unraveled your nerves with his magic. His kisses burned down your chest and between your legs. And that's when you realized that magic left invisible marks that you hadn't known existed. Your world imploded when he revealed his tongue, blue, glowing, and made of concentrated magic that consumed your very core the first time it touched your skin.

"I've never met anyone so sensitive," he chuckled as you orgasm the first time his tongue found your clit. "How many times can you do that?"

You lost count as you ripped off his shirt and clawed at his bones. His tongue was unrelenting until you couldn't breathe. You had to beg him to stop and still he persisted, "You can take more. Ride it. Open yourself to my magic."

You lost yourself in waves of pleasure as your last orgasm lasted for minutes? an hour? You knew it was an exaggeration, but all you could see was blue light when you closed your eyes. Your throat lost the ability to even make noise was your mouth echoed an impossibly long "o" that left you panting and gasping for air. You had no energy to wipe the smug look off his face, nor did you bother to move as he took down notes in the journal beside his desk. You let the soft fall of pencil scribbling on paper almost lure to sleep.

Eventually you regained the will to move, and you snatched the book out of his hands. He let you flip through it. He'd been writing down simple observations of your reactions to his touches for a while. He had theories, crossed out hypotheses, but the last page he was writing in didn't have much aside from a crude orgasm tally and a rough sketch of you lying sated and naked on his desk. The words "Minimum Effort. Maximum Result" was scrolled on the bottom.

"You're a naughty monster."

"Are you sure you aren't one as well?"

 "I see that's one of your theories."

"You fuck like a monster."

"We haven't technically fucked. Can you even-?"

A bright blue glow tented in his pants. "Oh... yes you can. Is it like your tongue?"

Sans shrugged, "Bigger, thicker... based on your earlier performance, I don't think you could handle it, kid."

You wrinkle your nose at the term, "What I can't handle is that nickname."

"Hm, how about "bunny" for the amount of times you hopped those hips against my mou-"

His phone rang, and he froze. You realized it was just a text. Sans explains that it's his partner. "He gets... distracted for long periods of time. I'm allowed to do what I want while he's like that, but when he texts..."

"I understand. I need to get home anyway."

But as you head home, you can't shake the tingling sensation that clung to your skin like a magical residue. You were sure your lover would feel it as she hugged you or cuddled you that night. But she didn't sense anything. She just asked you if you had fun, and you nodded. She left long claw marks down your back that night. "So next time he'll know who allows him to be with you."

If you had known then what you knew now, you would have stopped seeing him after that first time.

But you didn't know; so you didn't stop...

 

**Notes for the Chapter:**

> Tell me what you think in the comments below! The next chapter will delve more into Sans' partner, sexual magical experimentation, and talks about presents.
> 
> You can also check me out on Tumblr: [Dark_Crystal_Demon](https://www.tumblr.com/blog/darkcrystaldemon)
> 
> And check out my other works on AO3 [here](http://archiveofourown.org/users/Dark_Crystal_Demon)!


	2. ...A Detailed Affair

You know he's a skeleton. They live for hundreds of years. You are just his favorite toy of the moment. And you try to convince yourself that that's all he is to you too. After all, you're in a committed relationship...

You stare at yourself in the mirror and wonder what the fuck you're doing as you wrap a red Christmas scarf with white poms on the end around your neck to hide your lover's hickey. You see her in the reflection. She's digging through the closet behind you in an epic search for the right pair of shoes. You realize then that she's also been talking to you about her upcoming date with some other female human.

Human.

Is that not good enough any more? Your eyes hover over her beautiful curved hips. She is definitely not the cause of the bruises patterned along your thighs from an unforgivingly, hard pelvic bone. You push down on one of the bruises underneath your dress. You bite your lip as the pain blossoms into a reminder of Sans bending you over the lab table and thrusting into you with abandon as your moans echoed against the lab walls... You press another bruise and lick your lips as you remember your latest dalliance in the observatory on the top floor of the lab. You rode in his lap as you described your observations in the telescope. He really liked space. 

You really like him.

Your girlfriend just winked at you because she thinks your lustful gaze is for her in the mirror. You blow her a kiss. You are a really bad person.

She loves you. She trusts you even after you've "been working late." You told her there was a new discovery about dark matter. She doesn't care as long as you take care of her when you get home. You're not sure where you're finding the energy. Perhaps it's the magic. It makes your skin come alive and when he cums inside you...

You need to end this.

It had stopped being a casual fling some time ago. Last night you'd even started tracing the bones of your lover's spine while you cuddled her on the couch. She had only laughed, "Honestly, I don't see how a bag of bones can be that appealing. But I guess I have the best of both worlds to keep you in my bed, a hott ass and a skeleton on the inside."

You agreed and reassured your lover that it was just a phase. You distracted her with kisses and made her cum as her fingers curled in your hair... And you wondered if she realized you only ever played the submissive giver when you came back from the lab? You took care to wash the smoke from his bones before you made love, but the traces of his magic never left you. The longer your sessions with Sans, the longer it took for his magic to dissipate around you. Until it was gone, it was a useless endeavor to try and cum without him. You can't count how many times you'd faked it for your lover after work. You told yourself you made up for it in the morning when you could cum for real. But then... you felt like somehow, you were cheating on him.

 _No kissing. No marks._ I'm sorry, love. I didn't know there were other ways to be claimed. He wasn't like your other flings. You knew that after your first encounter, but the second time... h

He eyed the marks your lover had left on your body.

"Why does she do this to you?"

"It's a message for you."

"Oh is it?" The lights of Sans' eyes burned with a blue fire in the depths of his sockets as he scanned over your body, reading the challenge. His tongue appeared, bright, an intense blue within his skull. "Let me send a message back."

He'd licked every mark your lover had left on your body. His magic made them tingle and your heart almost stopped with the intense sensation as he made them his. Finally he hovered over you. Face inches from yours. You stopped his mouth with your hand. Bony teeth pressing against the soft skin of your palm.

"No. No kissing. It's the rule."

"Humans have strange rules," His tongue slipped between your fingers and twisted around your hand. Your lips parted as his tongue made your fingers slick with his magic. He pressed his hip bones against yours. You could feel his desire through the fabric of his pants. He presses himself harder against you. Your body hums with his magic covering your skin. His pushes his skull closer to your face. The back of your hand now pressed against your lips. It smelled like him. Smoke, ketchup... and you. His tongue pressed against the inside of your palm, pushing your hand further into your mouth.

His hands were busy releasing his belt. When the tip of his cock touched your skin, you felt like his magic was burning a hole right through you. Your hips jutted forward in excitement and he chuckled against your hand, "That's my little lab bunny."

Underneath his possessive gaze, you knew you should have stopped right then. But you and he both knew you should have stopped him a while ago: when he took up a challenge against your lover; when he claimed every part of your body with his tongue; or even now as he pushed the boundary of your mouth... But you didn't want to stop him.

Your hand muffled your moans as he traced his dick along your stomach. His magic teased your skin. Warm. Wet. Hungry. He grabbed your other hand and guided it around his cock. He was so girthy, you could barely get your hand around him. His magic buzzed against your skin and, for a moment, made your palm go numb underneath his power. He kept his hand over yours and guided you into a rhythm as he sat up and looked down at you. You kept your hand over your mouth, concentrating on his facial expression as he allowed you to set your own pace.

"Oh, bunny.... Oh yes.... Just like that."

Precum slid over your fingers and felt like a jolt of liquid energy. Your hand increased its speed instinctively and Sans closed his eyes. "Bun..."

He can't form full words. You blush at the compliment of making him feel so good. You wanted him to feel the way he had made you feel last night. Was that even possible? You increased the pressure around his penis, squeezing him around his base then spiraling your hand around his shift with a twist of your wrist. You reach his sensitive tip and cup your palm around him with a circular motion that elicits a growling moan.

His eyes are open now as you soak in more of his slippery pre-cum. Without thinking, you flip the palm by your mouth over and lick it. You taste his magic where his own tongue had been. It makes your mouth tingle. The sensation travels down your throat. You moan, enjoying the small taste of him. He watches you intently. You feel like your weaving a spell as you pleasure him with one hand and captivate his eyes with the other. When you'd made your hand thoroughly wet, you bring it up to join with your other one around his cock. Mixing your saliva with his magic, his penis to glowed brighter. Was that your imagination? But you were distracted by the loud moans coming out of Sans' mouth.

He started thrusting into your hands, his penis swelling as he got closer. You enjoyed watching him lose control. A smug smile came to your lips, but your breath caught in your throat as his eyes locked onto yours and you knew he was thinking of being somewhere other than your hands...

He yelled your real name as he came, his warm magical cum falling against your stomach, chest, neck... and lips. It sent shivers across your body as some of the magic soaked into your skin and spread across your nervous system. You licked the drops that fell on your lips, and Sans dipped his head down at a speed you didn't know he had. The tip of his tongue flicked across the top of yours before you could quickly hide it back into your mouth.

Sans chuckled, his breath playing over your lips. "Right... no kissing..." 

His phone vibrated on ground next to you. He glanced at it, but no urgency registered on his face. It must not be his lover.

"Does your lover have any other rules aside from your immediate attention when he calls?" you asked, making a whipping motion with your hand. Sans grabbed your hand with his own. You couldn't explain why, but you felt extremely vulnerable beneath his bony grasp. Something inside you knew he could have crushed your hand inside his, but he choose not to. 

He kissed your knuckles and rubbed his thumb over your skin while he contemplated your question. His eye lights got a distant look as he whispered, "He'd only have rules if he noticed you."

He shook himself out of his thoughts and began to trace some of his sperm on your stomach down to your clit. You gasp as his warm, wet seed surrounded you. His magic claiming your sensitive skin. " _Tibia_ honest, humans are never on his radar these days... and I'd like to keep it that way. Your _my_ lab bunny."

He started to circle your clit and you moaned at the attention. "Now let's see if we can break our record from last night."

 

**Notes for the Chapter:**

> Oh Sans... in the next chapter, it's about time to get to this party - and meet Sans' lover.
> 
> You can also check me out on Tumblr: [Dark_Crystal_Demon](https://www.tumblr.com/blog/darkcrystaldemon)
> 
> And check out my other works on AO3 [here](http://archiveofourown.org/users/Dark_Crystal_Demon)!


	3. The Party

**Summary for the Chapter:**

> Warning: This chapter gets a lot darker for the holidays.  
> Please check the tags.  
> Cheers to you and Happy Holidays!

Your lover kisses you goodbye as your cab arrives to go the holiday party. She cups your face in her hands and, for the first time, you think you see a hint of sadness in her eyes as she says, "Have fun tonight."

"Loni..." 

"Don't," Laeloni shakes her beautiful head with the strength that you had fallen in love with her for. You mimic her action, cupping her face in your hands, and bumping your foreheads together. She leans against you.

"I still love you." Tears threaten the edges of her eyes as you say it because you both know its one of the truest statements that still lived between you. It's why you haven't left. It's why you stay conflicted. Your world is being turned upside down by magic, but that didn't mean your whole life had to turn with it. You had become polyamorous to spice things up; this is just the toughest obstacle you both have faced so far.

"We'll talk some time. Not here. Not now. Not while you still come home to me. But no more lies. You're terrible at it."

"Yeah? Then why do you let me do it?"

"Because I love you, idiot. And love is blind. And stupid."

"I feel pretty stupid."

"Well you should. You haven't even noticed what I'm wearing," she says with a devious smile on her lips.

"Uh," you blink and pull your head back to look at her. She's wearing a long black trench coat with very steep stiletto boots. She unties her coat and reveals a leather outfit that makes you forget all about skeletons and their magical appendages.

"Laeloni!" 

"I've joined the BDSM community here. I... also... have many pets... and a few baby girls..."

"You want me to start calling you Mommy?" You just might to see her in that outfit more.

"No. Yes. Maybe? I've discovered a lot about myself while you've been... working."

"We do have a lot to talk about."

"Later, love. I can't keep my pet waiting. They need to be taken for a walk..." This is going to take some getting used to.

You look Laeloni up and down one last time, kiss her deeply, and turn towards the cab. "By Mom, I'll try to be home before curfew."

Laeloni rolls her eyes, "You're too disobedient for me to even want you as a child. Just... keep coming home to me, love. At least... for now."

"I promise," you lean on the door of the cab and watch her walk away down the sidewalk. You feel her bite mark underneath her scarf. _You're mine..._ Tears sting your eyes, but you aren't sure if they are for relief, sadness, or... something else.

"Tra-la-la, where to?" your driver asks in a sing-song voice. You sit down and close the door. Your eyes didn't leave Laeloni's back. You didn't know what the future would bring for you both, but the weight that had settled on your heart felt a lot lighter. It is time for both of you to figure out what you wanted. 

You take a deep breath and resolve to do just that. "MTT Above Ground Resort, please."

 

 

As the cab starts and Laeloni goes out of view, you instinctively look down at your phone. You're not sure why. Sans would never call you. You'd only seen him use his phone for his lover and his brother, Papyrus. You've never met Papyrus, but you've heard all about him, traveling the world as a guard escort for the monster's human ambassador. You've never seen his face light up more than when he talked about his brother and that kid.

"Why didn't you go with them?" you'd asked.

"Other people came back into my life," he'd responded getting that distant look in his eyes again. By "other people" you assumed he meant his lover. His hand was absentmindedly patting the phone in his pocket.

Now your phone is blinking with a news headline alert. It reads "Doctor W. D. Gaster's Holiday Appearance!"

Your finger immediately swipes at the screen to get more information. Dr. Gaster is a genius. You spent your last year studying his blueprints for the core system underneath the mountain that kept the monsters alive and save underground. He is the whole reason you decided to work at Royal Labs, but you had yet to see him in person since you were hired. He has his own personal lab below the building. Some say he just hasn't quite adapted to being above ground yet. But as you read the article, your hope is confirmed. Dr. Gaster was surfacing to come to the holiday party! Who knew he has a soft spot for the holidays?

Your cab stopped in front of the resort. You gawk at just how large it was. How did they build such a magnificent structure in only a year? You knew the monster royal family and your lab had been huge investors in the place, but you still marvel had how fast something can get done when large amounts of money were involved. 

"Beware the man who speaks with his hands. Tra-la-la!" the driver breaks your train of thought. 

"What?" you look up at him, but he doesn't look back at you. A hood covers his face and all you can see are red eyes staring back at you from the rear view mirror. Well that is unnerving. You quickly pay him and get out of the cab. 

Snow has started to fall again, and you hug your coat around you. You are suddenly very self conscious of the dress you had decided to wear. You hadn't really been thinking of who would be at this party. Ever since you found the box sitting on your desk, all you could think about was Sans changing his mind about the party. He had spent weeks telling you that giant work holiday parties weren't his thing. "Too much work socializing with so many people." But then you got back to your desk and there was his present with the party invitation tied to it.

This is going to be your first date outside of the lab. So you're in this ridiculously sexy dress and now you realize that somewhere in this building is the head of your entire lab and probably the entire board as well. You know Sans is a jokester, but this one went a little too far. He knew how much you respected Dr. Gaster, and if he knew the Doctor was coming... 

"Sans," you mutter to yourself, gritting your teeth and then taking a deep breath. You straighten your back, hold your chin up high, and head inside. The only way to save the night is going to be with confidence. You're a brilliant mind who also looks fantastic in this dress. Nothing wrong with that. This night just became less about Sans and more about your future.

Inside the lights and festivities of the lobby are breathtaking and distract you from your thoughts. The room is filled with the smell of a dozens of pines, apple, and cinnamon - with a hint of butterscotch? In the center of the lobby is a golden statue of the star Mettaton who is posed in his signature high kick into the air. He is an internet sensation and you'd be lying if you said you didn't watch his reality show with Laeloni at night. The statue is so life-like you can hear his voice in your head saying "Welcome darling, to the Magnificent MTT Above Ground Resort!"

The lobby buzzed with monster and humans mingling in the holiday spirit and pointing fingers at the press who were all, no doubt, waiting for the arrival of Dr. Gaster. You scan room for Sans' wide skeleton grin, but he is no where to be found. You do find the sign that guides you to the elevator for the party. You have to show a large guard dog monster your invitation and he pressed the bottom for one of the top floors. Two lizard monsters walk into the elevator with you. You all nod in recognition. You know they work in a lab on the same floor as yours, but you never really got their name. In fact, you didn't know most of the people at the lab. At least, not on any personal level. You stayed back to be with Sans most nights, so you very rarely went to many after work gatherings. And since you were sleeping with the boss, you felt you needed to work extra hard to prove you were there for your own merit.

But as you all stand there in silence, listening to Mettaton's Greatest Holiday Hits over the elevator speaker, you wish you had made more of an effort to get to know people. But then the awkward moment ends as the doors open to reveal a room that dazzles in millions of tiny white lights from glowing paths that looked like shining snow to the ceiling glittering like stars. Your eyes drift to the glowing dance floor that shifted patterns like a snowflake kaleidoscope while the band played the instrumental versions of more of Mettaton's tunes. 

"Can I take your coat, ma'am?" A robot servant wheeled their way over to you. All the servers on the floor had the same design based after Mettaton's original form without his legs. You heard they were operated by the ghosts from the underground. You peer closer at the box of lights and switches. You can't see anything beyond the metal, but somehow you can sense the monster inside it's core. "Ma'am?"

You hand them your coat. Did that machine just blush? Now that you were a part of the monster-led Royal Lab, you should really learn more about them besides skeletons. Speaking of, where is Sans?

You make your way down one of the glowing paths between sparkling, high tables that people are leaning around, drinking and eating hors d'oeuvres off trays held by cheerful servers rolling between the paths. You say hi to a few people and grab a stuffed mushroom off a tray and a glass of champagne from another. You're on the far end of the room still looking for Sans when you feel the hairs on your back rise and hear the excited whispers of the people next to you. They're looking back towards the elevator.

Dr. Gaster has arrived. 

He's a skeleton. In some Pavlovian way, that fact alone sets your heart a flutter. The only skeleton you've ever known up until this point has been Sans. But being a skeleton is where the comparison ends between him and Sans. Sans is short, thick boned, and has a perpetual grin that sets some at ease and others on edge. Dr. Gaster is tall, lean, and without inherent humor. He stands with the heir of some who knows they're important, a stoic superiority that makes others take a step back to give him space. But within that space is a settled and permanent darkness, a remnant from his time in the Void, a dimension the lab was just beginning to investigate. You heard his time there had left permanent scars. You can see some now: two large cracks carved in his skull from his eye sockets. The lights in his eyes are dim as they scan the room while a few servers fuss over him for his hat and coat.

His eyes fall on you and, for a moment, you think you see a flash of recognition, but his focus is mostly on your dress. Well, that is one way to make an impression with one of the greatest minds in the scientific world. You feel like the shadows around you are somehow getting closer. The lights dim, your heart rate quickens, and you wonder for a moment if you have met him before... but then the moment is over. His gaze continues across the rest of the room. You let out a breath you didn't even notice you are holding. 

He is intense.

You watch as scientists and board members flock to greet him. They walk him to an honorary table near the dance floor. The glowing path dims beneath each steps he makes. You can't stop yourself from watching him, but he doesn't look in your direction again. You decide now is not the time to introduce yourself. Your hand is shaking. You've never been this star struck before. You need to relax. You spot a buffet table. If Sans is here, he'll probably be around there. Though you doubt they have ketchup packets lying around. You're right, of course, there are no ketchup packets, but there is also no Sans. You sigh and grab some light snacks. You're not really all that hungry, but it would look silly to leave with nothing in your hand. You find an empty standing table and lean on it. You focus on the band and wonder what your next move should be. You hadn't planned this evening without Sans. You look down at your phone again even though you know he wouldn't leave you a message. You get caught up in the net until -

You smell smoke. Cigarette smoke. A familiar brand that makes you smile and take a deep breath of the remnants of that horrible habit. "Sans."

" **Interesting assumption** ," the voice behind you is deep and resonant with a subtle hiss that sinks into your skin and makes the blood in your veins run cold. Who...?

You want to turn around, but you can't. Not because of fear. You physically can't move. You look around the room as darkness dims and blackens all the lights around you. You look around for help, but the room is frozen in time. Soon you can't see anything but black void...

Void. The smell that clings to Sans. The lover you've never met who "gets distracted for long periods of time" ... and you realize you've never seen Sans leave the lab after he gets called. _No way..._

"D-doctor G-gaster?"

He chuckles. It echoes through his hollow frame and reverberates through the darkness around you. You can feel him bend down, his face near your ear as he makes an exaggerated sniff. " **Humans are so easily afraid of the unknown. What a delicate frightened creature you are**."

Your knees go weak, but he's now pressed against your back. You can feel his suit through the fabric of your dress. His arms wrap around your waist. " **You smell like him,** **human**."

You can feel his tongue forming. All your time with Sans has fine tuned your sensitivity to magic. But Sans' magic was not as strong as his. Your skin burned as his long, slimy appendage licked along the exposed skin on your shoulders... and then a different appendage appeared from the darkness. In your peripheral you can see a tentacle, translucent with purple magic glowing within it's core. It pulls the scarf from your neck and you hear him chuckle " **How primitive.** " as his tongue sears across the hickey Laeloni had left on you. It's what Sans would have done...

Sans...

His head moves up to your ear as his wraps around your neck. " **How fun must you be for him to miss my call?** "

Your mind froze at his words until you hear an echo in your mind. _I'll get it in a minute._  Sans' words as he lost himself inside you a couple nights ago. You realize you hadn't seen him as much since, but then he'd left the dress at your desk...

" **Thank you for accepting my invitation. It was time for us to meet**." The tentacle tightens around neck. You gasp as fear takes over. The power that had held you in place fell away. You reach up to stop him, but more tentacles appear from behind you. They wrap around your wrists and up your arms, holding them captive in mid air. His hands grip your waist more firmly against his body. You want to scream, but the tentacle around your neck tightens enough to stop your vocal chords... but not tight enough to kill you.

" **What a bright power, _bunny_. Sans should have known better than to keep you from me.** " His magic burns into your skin like a toxin. You feel your body flush, confused. The instinct to flee is triggered by his assault, but his magical presence against your skin triggers a different set of responses. Sans had trained your body well. Ever since his tongue has touched your skin, your nipples hardened. You are sweating in fear and arousal. Ashamed of the slickness between your legs, you try to tell your body _he's not Sans_. 

Another tentacle wraps around your knee and starts to slither past the hem of your dress.

"N-n-ooo!" you manage to choke out. 

" **Oh? Did you think you had a choice? I apologize for the misconception.** " You can hear a satisfied hiss in your ear as his tentacle slides along the inside your already wet thighs. You blush in shame. " **Mmm, aren't you a well trained pet?** "

You shake your head. This can't be happening... You feel his tentacle's tip rub along your lips. He circles himself along your entrance. His magic sends shivers up your spine. You can't control the need he's eliciting from your body. He slides along your arousal, his tip caressing your slit. You bite your lip and fight the urge to open yourself to him.

" **This is a lesson, sweetheart. When I send a message, there is never an option to ignore it,** " He snarls as he rips himself inside of you with one tremendous thrust. 

"AH!" You cry out, tears well in your eyes at your helplessness. His tentacle writhes inside you. You try to squirm, but that only increases the restraints on your wrists and neck.

" **So this is where he's been spending so much of his time.** " He pushes against your walls and you moan despite yourself as he begins to stretch you with his exploration. His magic pulses inside you and you arch your back against him in disgust and desire.

" **That determination...** " his hand travels up your body to your chest. His tentacle retreats from inside of you and then thrusts itself back in with a force that leaves you breathless. Your chest rises into his hand. His hard, calloused bones cut at your skin as you feel a pull from deep inside your chest. " **Come to me.** "

His tentacle starts to thrust in you with a steady rhythm that makes it hard to concentrate on anything else. It grows, stretching you further and hitting the spot inside you that makes your mouth open in a silent "o". Another tentacle starts to play around your clit. What? Does he actually want you to-?

" **Good girl, just a little further.** " You're taken aback by the compliment. It feels like his pulling your heart out of your chest, but with all the stimulation you're finding it hard to concentrate. His tentacle still firming around your neck, you gasp for air. 

You're excited. You're dying. You're rising. You're... you're losing your grip as pleasure builds inside you. " **Yes, give yourself over to it. Give me your soul.** "

What?!

But his tentacles are relentless and you feel yourself losing control under the vibration of his magic. Your legs go weak and he holds you up with his tentacles as you cry out. Your chest pushes itself against his hand and a red light fills the darkness. " **Oh pet...** " He's still inside you, caressing you in his joy. 

The crack on the side of his skull presses against your temple as he leans his head against yours over your shoulder. His hand raises the light to your face. It's a shining red light shaped like heart you'd see on a Valentine's card. His tentacle finally slithers away from your neck, a bruised collar left in it's wake as it curls around your waist instead. You gasp for air and your - soul? - pulses bright with every breath. Is that really you?

With a satisfied hum that's emphasized by his twitches inside you, Gaster raises his other hand above your soul. Its light highlights all the micro-fractures across his bones and the large gaping hole gouged out of his carpals in both hands. He looks like he's falling apart; but the strength of the tentacles around your body, and the magic that racing along your skin indicates otherwise. You realize you never regained your footing from earlier. You're still being help up by his tentacles like a puppet on a string. You try to move, but he tightens around you. Inside you feel him press against your walls, pushing you against his body. " **Sans has been selfish, little bunny."**

"Don't call me- ah!" A rough bony finger taps your soul and it makes every cell in your body jump.

" **Tsk, that is not the tone you use for your new master, bunny.** " You whimper as his finger traces patterns along your soul. It makes you ache and your body shake with revulsion. You suddenly feel sick with the thought that he is still inside you, his tentacles burned along your skin as his magic seeps further into your skin.

"No!" Your soul bursts with light at your declaration, but all you hear is Gaster's laugh. A real, harrowing, sonorous laugh that fills you with dread even as his tentacles left your body. He pulls your dress back down to its proper position and turns you around to face him. The smile carved in his scarred skull is splashed with red light from your soul. It's crimson glow is the only light inside those hollow sockets of his as he gazes down at you. 

" _ **Bunny**_ ," his voice is maliciously sweet and condescending. " **You never had a choice.** "

His hand closes around your soul and pockets it inside the fabric of his suit, pressing against his rib cage. The world of darkness disappears and the white glow of the party returns with the sounds of people laughing and dancing as the band plays the latest holiday hit. You're caught up in the return on smells and sound, but are brought out of your shock by the scarf being placed back around your bruised neck, the only visible mark that anything had happened. You bring your legs together. You can still feel the imprint of his tentacle squirming inside you. 

"Give it back," you demand but Gaster just shakes his head, ignoring your pained expression. You feel like you're being split in two. 

" **My, my, so disobedient, but we'll fix that** ," Gaster places his hands along your shoulders. Then his voice drops to a deadly whisper as he says your real name. " **I do not abide scenes, pet. You will smile like the happiest whore in the world as I walk you out of this party."**

You obey.

You don't know what else to do. You put your arm around his back and lean your head against his chest, where your soul beat against the fabric. You smile and wink at co-workers who give you weary smiles or judgmental glances. But your thoughts are focused on the red light dimmed by the darkness that clings to his bones like the smoke woven into his suit. You can feel dark tendrils licking your soul and it makes your knees give out. Gaster catches you around the waist and dips his head low like a lover whispering, " **Don't worry, pet. You'll get used to it.** "

 

**Notes for the Chapter:**

> Last chapter will be up by Christmas!  
> Let me know what you think in the comments below. 
> 
> You can also check me out on Tumblr: [Dark_Crystal_Demon](https://www.tumblr.com/blog/darkcrystaldemon)
> 
> And check out my other works on AO3 [here](http://archiveofourown.org/users/Dark_Crystal_Demon)!


	4. Master...

**Summary for the Chapter:**

> *fans self* Bringing back the slightly ambiguous consensual for the holidays... 
> 
> Sorry for the delayed posting. This chapter just got me a little ... distracted. I hope you enjoy it.

**Notes for the Chapter:**

> ***This is not the last chapter. I've changed this fic length. There will be a Chapter 5!***

Your passage through the resort is a blur. Every part of your body is attuned to your soul that lies just under your ear. It pushes against the fabric of Gaster's suit, but it can't escape the darkness. Every second without it is making you feel weaker. But just as his darkness cradles your soul, Gaster holds you firmly to his side. He dips his head down low with a lover's whisper, " **You're almost there, pet. Keep smiling for the cameras. Good girl.** "

You freeze against Gaster's side as a limo pulls up on the street. You look up at him for the first time since he'd taken your soul. You recognize the void deep inside his sockets. He'd taken you to that dimension, but perhaps you've never left. His grip on your waist tightens as his dim eye lights mock your shock. " **Shhh, pet. Now get in the limo.** "

You comply, but a wave of indignation gives you the strength to separate yourself from him and sit as far away from him as you could. 

An amused smirk spreads thinly across his skull as he shakes his head at you. You feel the painful pull of your soul, upset that you are so far away. You can feel it shine bright with your anger, but then Gaster begins petting the breast of his suit, where your soul lies. He's not anywhere near you and yet you feel him everywhere. He says, " **So much determination, pet. That's good.** "

You condescending... "I do not belong to you!" Your soul blazes in his suit as the limo starts to move. You rock in your seat feeling very anti-climatic as Gaster continues to sit there, petting your soul. It's massaging all of you at once. Gently pulling away the tension, you feel fingers dig deep into those tight spots between your muscles. You drop your head down so that he can't see the pleasure on your face as your body gives in to the kneeding sensation. You close your eyes. You feel a purr deep in your throat as your body begins to relax. No...

You can't stop him. You don't want to. But you have to! Don't you? 

He choked you... 

into an orgasm. 

No! That is not okay. He forced himself inside you... 

and made you cum. 

The strokes of his fingers are effecting your judgement. You glare at the floor beneath you. Y _ou have to get your soul back..._

" **Your soul burns bright, I can feel you trying to lie to yourself. But you cannot hide your intentions from me.** " There's a sound of flapping pages in the air and then a thunk as a familiar notebook falls at your feet.

Sans' notebook. 

It fell open to a drawing of you kneeling on the ground with Sans belt around your neck. " **You enjoy being punished, pet.** " The truth of the statement settles in the air between you as he continues to stroke your soul. You hear the click of a lighter and the smell of his cigarette elicits a primal response within you as your body connects the smell to Sans...who smells like Gaster. You've always been smelling _him_. It's like he's always been there. And, as the pages of Sans' notebook start turning by themselves, you realize that if he's read this notebook, it's like he really has been with you both. 

" **You enjoy being owned, but your loyalty falters under weak leadership. It is to be expected from a determined soul like yours, pet. You need a master that can bring out your true potential instead of squandering it.** " You look up to glare at his smug face, but your eyes are caught on their way up. He's loosened his tie and unbuttoned the top of his shirt, revealing the darkness-encased bones within. A faint red glow from your soul outlines his sternum, upper ribs, and clavicle as he casually lounges in front of you with his cigarette in one hand and his other continuing to stroke your soul. You find yourself mesmerized by the movement of his phalanges. Your heart beats in rhythm to every stroke, and you suddenly understand his true intentions, filtered into your soul. 

He's... _courting you_. You don't know what to say as he takes another drag from his cigarette. The smoke curls around his skull. Gray tendrils swirl down his vertebra and caress your soul, that beckons you to join it inside him.

He says your real name in his deep, sonorous voice that brings your eyes to his. The dim lighting of the limousine fades away as the Royal Scientist of Monsters propositions you with his eyes. Reality disappears as dark symbols filled your mind. **_Let me be your Master_**.

Your lips part to answer, but your throat has gone dry. You lick your lips and his eyes follow your tongue. You take your time bringing it back inside your mouth. When you do, his eyes travel down the curve of your neck. You pull off your scarf away slowly. He watches hungrily as the fabric falls away and reveals the bruised collar along your throat. Your heart pounds further, to the point that you are sure he can hear it beat from across the limo.

" **Come here** ," he puts out his cigarette and pats his leg. 

You sit up at the order, but you can't stand in the limo. 

" **Crawl.** " The words snap you out of the spell he's cast around you. What are you thinking? A master? You'd barely let Laeloni play that role and you loved her. Punishment and markings were one thing...

"You've got to be kidding me. You really think I'm going to crawl to you?"

" **Yes.** " His hand continues to stroke your soul, unfazed by your sudden outburst. " **Because you want to.** " 

Sans' journal floated off the floor. It's pages magically flipping in front of you. Each one reveals one detailed picture after another. Why had you let Sans make a journal like this? " **You want to relinquish control.** "

He pulls out your soul, floating above his hand. Darkness swirls around it. You can feel the shadows around you wishing to do the same. " **You can't hide from me, bunny.**

" **Top scores in your graduating class. Highest recommendations from three of the leading scientists in experimental physics and astrophysics, all mentioning your remarkable work ethic. And since you've joined my lab, you've manage to prove them all correct with more hours in the lab than all the new recruits combined,** " he pauses as you absorb how much background research he had done on you. " **Though I am acutely aware of your extracurricular activities with one of my most brilliant scientists, your work has proven useful and yielded results that set you on a track that you have undoubtedly already planned for far in advance."**  Except this. You never planned for this, and as the pages turn before your eyes, you wonder how you ever let this happen. How could you let sexual pleasures get in the way of your dreams? 

But you already know the answer as Gaster uses his magic to pick you up and float you over to him. The magic tingles across your already sensitive skin. You feel weightless. You feel cute. You feel... owned. 

Your dress comes up above your waist as he sets you in a straddle across his hips. Your soul float between you. Instinctively you raise your hands to cup it on either side, but Gaster's hand remains below it. He curls up two fingers to caress the bottom edge of your soul and you feel it intimately within you. 

"Ah!" you bite your lip to try and stop the sound. But Gaster's other hand cups your chin and raises your face to his. 

" **The time for inhibiting yourself is over, pet. Let yourself feel everything.** " His fingers moved again and you let yourself moan loudly. The hand on your chin drifted down your neck, leaving a gentle trail along your skin, along your side, until finally they cupped your ass and squeezed as he fingered your soul again. 

"AH!" His face is so much closer now as he pressed you against him. Your knuckles push against his ribs; your soul still blocked from reentering your chest by his interloping fingers that now also rested between your breast. Your breath bounces back onto your face from his bony, non-existent lips... lips of a monster who cradles your soul...

" **Human rules no longer apply, pet. When it comes to desire, you must always allow yourself to succumb to it.** "

What is he doing to your soul? His desire surrounds you. It's intensity is overwhelming and you find yourself grinding against his rigid pelvic bone under his suit. " **Yes, pet.** "

You feel yourself getting wet and blush as it begins to soak into his clothes. He's pulling you closer, raising you higher. Your breathing becomes embarrassingly loud, but you let yourself go, literally. You release your hold around your soul and grab his skull, pulling him into the most passionate kiss you've ever experienced as he continues to hold your soul between your breasts. You know you are saying goodbye to Laeloni and maybe even to Sans, but you can't find the regret within you. His power and control are intoxicating as his tongue appears, numbing your lips with his magic. You open your mouth to let him inside. He devours you. You soul is warm between his fingers as you let him explore your mouth deeper. 

Then you feel his long digits begin to slide below your ass, parting your lips. You hear his pants unzip and feel, rather than see, his large, tentacle member grow straight into you like a budding plant.

You moan with his tongue in your mouth as he fills you. You spread your legs wider, trying to take more of him. You can't fight the feeling of wanting him within every part of you. You don't want to fight it. His fist closes around your soul and you press your breasts around him. 

Hard, rigid, and full of power that radiates into your core, his cock twitched inside you and his kiss stopped long enough for him to say, " **Don't stop, pet. Show me your desire.** "

You raised your hips to pull his shaft out all the way to the tip. You feel other tentacles around you now, dark tongues caressing your thighs, waist, breasts, even teasing your neck, just behind your ear. You slowly let yourself fall back around him. Your breasts pressing down his ulna to his elbow. Your soul now only visible between his metacarpals. 

You watch as he bends his head down to his hand, which opens before him. Your soul beat with the quick rhythm of your heart. Darkness swirls inside it now, but before it can register in your mind what that means, his tongue wraps around it and you moan as the intensity of his magic pulses around and inside you. 

You scream at the top of your lungs as the sensation pushes you to every edge of pleasure. Nothing has ever made you feel so complete. You surrender to it and lose yourself under his control as tentacles guide your movements around him. You can't think. You can barely breath. Your only thought is on how amazing it feels. You don't stop. You can't stop. You just want more. Deeper. Harder. Faster. More. MORE. Yes! YES! AHHHHHHH!

Gaster begins to lose his calm as your orgasm goes on and on. Your soul slips out of his grasp and shakes between your synced moans. It reunites within your chest right as Gaster cums inside you. You shudder uncontrollably around him as his magic permeates through every part of you. Claiming you. All of you. He holds you tight against him, kissing your chest where your soul re-entered. " **You're mine now.** "

"Yes, master."

**Notes for the Chapter:**

> I just couldn't say no to more time with Gaster... I hope you enjoyed it too. Next chapter we'll see what's happened to Sans. ^_~  
> Let me know what you think in the comments below. 
> 
> Shout Out to Golden Thread's [Cage of Bones](http://archiveofourown.org/works/6809974/chapters/15549688). I can't get this psychological smut out of my head. If you dig this Gaster, go check out Cage of Bones. It's going to rock your world. It's rocked mine. 
> 
> You can also check me out on Tumblr: [Dark_Crystal_Demon](https://www.tumblr.com/blog/darkcrystaldemon)
> 
> And check out my other works on AO3 [here](http://archiveofourown.org/users/Dark_Crystal_Demon)!


	5. Family

**Notes for the Chapter:**

> Warning to binge readers: the steaminess continues from the last chapter. You might want to take a breather. Or not. I'm not your doctor. But don't blame me for over-stimulation.

Gaster keeps you on his lap. You... didn't mind. You are already used to the smokey smell that surrounded him from all your times with... Sans. You have so many mixed emotions as you hold onto his lover's body. Not just his lover. Now he's your lover. Owner. Master. 

Gaster strokes his fingers down your back and you nuzzle your head into his neck. This feels too right to be wrong. Your heart beat syncs to the pulse of his magic. You can feel each of his ribs under his clothes. They press against your breasts, that squish around his hard bones. You feel your soul rest at the border between your chest and his. It floats just inside yourself, but wants to be inside him as well. 

The want grows into a need. It's as if every part of your body is being reawaken. Even though you just had sex, you can feel yourself wanting him again. You're becoming hyper aware of every place his body presses against yours. You squirm a little as the sensations becomes stronger. 

" **Mmm, something wrong, pet.** " It isn't a question. His hands slide under your dress and pull it up over your head. You welcome the action. Your body feels like it's on fire. The only release comes when you touch him.

"What have you done to me?" You undulate your body against him as the desire within you increases. You express your need by licking the sensitive area where his thick vertebrae meet his rib cage. You'd learned a lot about skeletons in the last few months, but nothing had prepared you for the ache you now feel. You want him to feel the same. His bones shiver under your lips, and you can feel his excitement as if it is your own. It's like your soul is a medium, filtering his enjoyment throughout your body. 

" **Your soul is recognizing its new master. It's linking itself to my needs.** " His needs. His needs are relentless. You lick along his clavicle to the top of his sternum and suck. His bones vibrate in your mouth with their magic. Your tongue can feel every micro-fracture he has endured. His bones taste like smoke with metallic hints of iron and steel from the blood. You don't stop as you feel his darkness enter your mouth and travel down your throat like a thick mist inside you. It travels down to your soul and mingles with the darkness already there. You have never felt so owned... nor so connected to your body. 

You've never felt so whole.

Your body hums with desire. The more you taste him, the stronger your need. "Why does this feel so... _good_."

Gaster chuckles at your enthusiasm, and pats your head; but his grip tightens under the ministrations of your mouth. After everything he's made you feel in the last couple of hours, you enjoy the empowerment. You start to unbutton more of his shirt, kissing down his sternum. He let's you. His hand trails down along your spine. You arch your back under his touch. In order to reach his lower ribs, your body has shifted down his legs. Your thighs sit just above his patellas. Your ass is to far for him to reach and yet... You feel his fingers slide right into you. You moan against his bones and bite playfully at one of his lower ribs. " **I wondered if your sensitivity to magic would also intensify your awareness of the soul bond. You have not disappointed.** " 

You can't focus on his words when you feel him examining how slick you are. How is he doing that if both his hands are on your back? You look down and see a hand floating by itself between your legs. You vaguely remember images of Dr. Gaster working in his lab with duplicates of his hands floating around him. Sometimes he would even use them to sign his answers rather than bothering to talk. The photo image in your mind changes from a machine on his lab table to you. Now you are his focus, his experiment... He curls his fingers inside you. 

His.

You are his.

" **When I am pleased, it pleases you.** " He continues his explanation. It's true. You can feel the truth inside your soul. Every tremor of his bones underneath your mouth is mirrored within you. You squeeze his fingers inside you and instinctive reach down to circle your clit, throbbing now for attention. Another floating hand stops yours and brings it back to his rib cage. " **No, pet.** "

You whine and bite his rib harder now. It sends a jolt inside you that clenches the muscles in your stomach, letting you know he liked it. But it only teases you further. His hand inside you wasn't enough as your body radiates this new pressing need. You buck into the air between his legs. You want you press your body against his; but you can't when you're bent over him like this. Your mouth surrounds the bottom tip of his sternum, the xiphoid, and you moan as your body resonates his desire. The rough tips of his phalanges dig into your back as he moans. You can't stop the sense of pride in making him react this way.

There's a deep pressure building inside you. But it's not from his hand. He's too far distracted to move it much. It's mostly just anchoring within you, and, you suspect, keeping you where you are if you decided suddenly to move. No, this pleasure is a large wave within your core. The feeling stimulates your clit and other sensitive spots within you "Oh my..."

" **Don't stop.** " He growls, and you eagerly obey.

Skeletons didn't need genitals. Their bones were sensitive all their own if you knew where to stroke. You take his whole xiphoid in your mouth, your tongue lathing the back of his sensitive sternum. You trail your hands down to the base of his spine and begin to stroke his coccyx. You nearly lose your grip as a new wave of pleasure pulses around your body.  

You look up at him and watch his composure break. A pet's greatest reward. He says your real name as he throws his head back and his entire body rattles in a skeletal orgasm that ignites your own. 

"Oh wow..." you marvel with his bone still in your mouth. Gaster's extra hand disappears inside of you as he pulls you back up into his lap. Your fingers curl around his ribs, the darkness twirling around your skin. He kisses your forehead with a tenderness you didn't know he had. 

"You have... exceeded expectations, pet." He strokes your head. You smile into his neck as the compliment settles over you. 

"Yeah, she's a real _overachiever_..." Your back straightens with the sound of Sans' voice behind you. His sarcasm raises the hair on your skin. You're afraid to look behind you, but you do. His eyes stare at you in the window, now open, between the back of the limo and the driver. You can't read his expression under the shadow of his driver's cap. 

He'd been the driver... How long had the limo been parked for? Or had he been watching the whole time?

You try to move off Gaster's lap, but he tightens his grip around you and holds you where you are. You blush glancing down at your dress on the ground next to Sans' journal. 

"Sans..."

" **Nah, uh, huh, pet. We don't talk to naughty boys who hide things from their fathers.** "

Father-? You almost asked aloud, but Sans would't have heard you. He'd disappeared and then reappeared in a seat near you both. He rolls his eyes, a certain humor returning. "He has a daddy kink which he is, apparently, now expanding."

" **Mmmm, this brat phase of yours is getting tiresome. But it has been a long time since I've had a pet. You've trained her well.** " Gaster's fingers trace circles along your back. You take a deep breath not sure what you should do. The chill of the winter creeps into the limo and you feel your nipples perk up. Gaster dips his head and bites your sensitive skin harder than you were expecting. You yelp and hear Sans gasp beside you. " **Yes, so sensitive. She'll fit in nicely.** "

Then, without warning, you were floating in the air from Gaster lap to Sans'. His arms surround you immediately. He's very tense. His body is shaking with pent-up emotion.

" **Here you go, son. Clean her up and get her dressed into something more elegant.** " Gaster says as he zips his pants and buttons up his shirt. " **I had dinner scheduled late tonight, but I expect you both to be ready within the hour.** "

He opens the door. " **Also, I had the purple room prepared for her. Your journal mentioned that is her favorite color. It seemed the appropriate choice.** "

Sans' brow raises, but his tone is deadpanned, "So much effort, _Dad_."

"A room? I don't need a room," you say, slightly irked by how you are now suddenly being talked about rather than talked to. As if he can read your mind - maybe he could now? - Gaster looks you straight in the eyes. You can feel his grip on your soul tighten inside your chest. 

" **You're family now, pet. Where else would you stay?** " Gaster says, not waiting for a reply as he walks out of the limo and stretches. He lights a cigarette. " **I'll even get you your own lab.** " 

He crosses through the rather large garage to a set of double doors that look like the ones at the lab. Maybe that's where you are? The lower levels of the lab underground? 

When he's out of sight, Sans begins to whisper urgently in your ear. "You need to get dressed, get in that driver's seat, and run, Bunny."

"What?"

"I'm sorry he found you, but if you value your freedom, you need to do as I say, kid. Grab your lady, if you want, but head straight out of town. Get out of the country. Cross an ocean. Make it so difficult to locate you that he gives up. He won't leave the lab for long. He can't. I'll distract him for as long as I can, but you need to be out of this city within the hour."

He pushes you off his lap and hands you your dress. Where would you go? Would you really uproot Laeloni because of your decisions? Would you leave behind all your work? The research you started? Your new top connection to the scientific hierarchy? He said he would give you a _lab_. You shake your head, "I'm not leaving."

"This isn't a joke, kid. Nothing's free," Sans' eye lights fall on your chest. You know he's looking inside you at your soul. His eyes were full of guilt. You've never seen him like this. "He's already taken so much from you. He won't stop until there's nothing left."

"My whole life is in this city," you grab Sans' hands. They're shaking and so are yours. The magic in his bones tingles your skin. Magic. You can feel it all around you now. You're not a fool. It's obvious that Gaster is a bit unhinged. You can feel it in your soul. His darkness is the first thing he showed you....

And it excites you. Its dangerous and stupid, but you've felt more alive in the last few months than you have in years. Sans woke you up from a monotonous routine when his magic sparked your skin the first time. You kiss his phalanges in your hand. "I can't go back to a normal life now, Sans. I won't. I'd rather see where this rabbit hole goes."

"Bunny..." Sans cups your face with his hands, the pun, for once, not his intention. Bunny. That's who you are now. You never thought you'd be in this position, but you just made a deep emotional link with one of the top scientists in the country and you have a relationship with one of his leading researchers...

"I want to be owned by both of you. And if it's really so bad in there, then I'm not leaving you behind, either."

"By the stars, you're beautiful when you're determined," Sans bumps his forehead with yours and then he kisses you. Your first kiss together. He must have seen Gaster break Laeloni's rule, but Sans isn't like Gaster. Gaster had ravaged your mouth; claiming it as with his own. Sans' is a chaste kiss. His teeth press against your lips. A thousand moments race through your mind. A thousand times you stopped short of kissing, pretending all that was between you was lust. Oh Sans...

You open your lips and dart your tongue out. He does the same. He presses you down along the seats. You wrap your legs around him. He grinds himself against you, but then he stops. "I-I'm going to need permission from now on."

You pout, but nod your head in understanding. There are a lot of rules you were going to need to learn. 

"Are you sure you want to do this, bunny? This family is stranger than you know. And I'm not completely sure of Gaster's intentions -"

"Sans," you silence him with a finger to his lips. There is no turning back now. You've made up your mind. "Take me to my room."

**Notes for the Chapter:**

> So um... this could keep going... but we've broken the kissing and marking rule so this arch is done!
> 
> If you want me to make this the first arch in a series, let me know in the comments. The more love this fic gets, the higher on the priority list it goes. ^_^ The second arch would be full of Gaster/Sans/Reader, the transition to living in the lab, starting a "special project" with Gaster, and the return home of Papyrus.
> 
> Thanks again to RavenZaphara for putting this Holiday Collection Challenge together. And a shout out to everyone who participated! I've really enjoyed a lot of the fluff and love. 
> 
> You can also check me out on Tumblr: [Dark_Crystal_Demon](https://www.tumblr.com/blog/darkcrystaldemon)
> 
> And check out my other works on AO3 [here](http://archiveofourown.org/users/Dark_Crystal_Demon)!


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